1. Field of Endeavor
The present invention relates to an imaging spectrometer, and more to an arrangement of optical elements to provide a dual waveband imaging spectrometer, in this case covering the visible through short wave infrared and the midwave infrared in one instrument.
2. State of Technology
U.S. Pat. No. 5,717,487 provides the following state of technology information: “A spectrometer is a known instrument for examining the spectral characteristics of light. Light emitted from or reflected by an object is received within the spectrometer and separated into its spectral components, such as the red, green and blue colored spectra as occurs in equal intensity when standard white light is so analyzed. The intensity of each such spectral component of that received light may be readily observed and measured. Each element of nature, molecular components, organic and inorganic compounds, living plants, man, animal and other substances is known to emit a unique spectrum that may be used as an indicium to identify the emitter.” The disclosure of U.S. Pat. No. 5,717,487 is incorporated herein in its entirety for all purposes.
United States Patent Application No. 2002/0135770 published Sep. 26, 2003 provides the following state of technology information: “Imaging spectrometers have been applied to a variety of disciplines, such as the detection of defects in industrial processes, satellite imaging, and laboratory research. These instruments detect radiation from a sample and process the resulting signal to obtain and present an image of the sample that includes spectral and chemical information about the sample.” The disclosure of United States Patent Application No. 2002/0135770 is incorporated herein in its entirety for all purposes.
U.S. Pat. No. 6,078,048 provides the following state of technology information: “In recent years substantial effort has been directed to the problem of detection of airborne chemicals. The remote detection of airborne chemicals issuing from exhaust stacks, vehicle exhaust, and various exhaust flumes or plumes, offers a non-intrusive means for detecting, monitoring, and attributing pollution source terms. To detect, identify, and quantify a chemical effluent, it is highly desirable to operate at the limiting spectral resolution set by atmospheric pressure broadening at approximately 0.1 cm−1. This provides for maximum sensitivity to simple molecules with the narrowest spectral features, allows for corrections for the presence of atmospheric constituents, maximizing species selectivity, and provides greater opportunity to detect unanticipated species.” The disclosure of U.S. Pat. No. 6,078,048 is incorporated herein in its entirety for all purposes.
U.S. Pat. No. 5,880,834 provides the following state of technology information: “There are three problems in designing an imaging spectrometer where light in a slice of an image field passing through an entrance slit is to be diffracted by a grating parallel to the slit and imaged onto a focal plane for display or recording with good spatial resolution parallel to the slit and good spectral resolution perpendicular to the slit: 1. Eliminating astigmatism over the spectrum on the image plane. 2. Removing field curvature from the spectrum focused onto the image plane. 3. Obtaining good spatial resolution of the entrance slit which involves eliminating astigmatism at different field angles from points on the entrance slit.” The disclosure of U.S. Pat. No. 5,880,834 is incorporated herein in its entirety for all purposes.
U.S. Pat. No. 7,414,719 for an imaging spectrometer wide field catadioptric design issued to Michael P. Chrisp Aug. 19, 2008 provides the following state of technology information: “The present invention provides a compact imaging spectrometer with an immersive or reflective diffraction grating that compensates optical distortions. The imaging spectrometer comprises an entrance slit for transmitting light, a system with a catadioptric lens and a dioptric lens for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through the system for receiving the light to the detector array. The compact imaging spectrometer uses smaller cryogenic coolers facilitating its using in portable (man carried) gas detection systems and in small unmanned aerial vehicles for remote gas detection. These instruments have application for Homeland Defense to check for the presence of biological or chemical weapons without entering the contaminated areas. These instruments can be used for pollution detection, and remote sensing of agricultural crops, and geological identification. They can also be used for the remote monitoring of industrial processes. The wider field of view of this design enables larger swath widths for the remote sensing of larger areas with single pass overflights and is extensible to take advantage of larger format or mosaiced infrared detector arrays.” The disclosure of U.S. Pat. No. 7,414,719 is incorporated herein in its entirety for all purposes.